The use of touch screen devices has grown in popularity via devices such as smart phones and tablet computers. However, a partially sighted or blind person may not be able to use a touch screen device.
One major drawback of the touch screen devices is that they cannot be adapted to the Braille system or even use tactile keys. Where some basic learning could master a hard key photocopier user interface, it is now impossible due to all of the possible options presented by soft keys on a user interface of the touch screen device. For example, a software upgrade could completely reconfigure the keys and render the touch screen device unusable without further re-training.